For programming bipolar ROMs I need a programming voltage of U=27V,30V,33V and an input voltage of U-7V. My first idea was to use a Zener diode in series to drop 7V at the diode. However, the needed current of at least 230 mA is too high for usual Zener diodes.
Is there a simple way to get the 2nd voltage with a transistor?
Might it also work with a negative voltage regulator like the 7905, with a zener somehow to generate -7V with respect to the U rail and then use this negative voltage but with respect to the real ground?